Skip known-failing test (see BZ 1154803)

Issuing a PUT request to the /users/:id API path will fail if the request
includes the `auth_source_id` parameter. The API doc states that this
parameter is acceptable, but the application returns an HTTP 500 error with this
message:

    auth_source_id is not allowed as nested parameter for users. Allowed
    parameters are auth_source_ldap_id, role_id, location_id, organization_id,
    usergroup_id

Test results:

    $ nosetests tests/foreman/api/test_multiple_paths.py -m 'test_put_status_code_.*_User'
    S
    ----------------------------------------------------------------------
    Ran 1 test in 0.636s

    OK (SKIP=1)
Drop method sleep_for_seconds

Method `sleep_for_seconds` is used in only one place. It causes the current
thread to sleep for somewhere between N to N + 1 seconds, inclusive, and this
behaviour seems to serve no purpose where it is used. Drop the method and just
call `time.sleep` as needed instead.
Merge pull request #1598 from Ichimonji10/cli-refactor

Drop method sleep_for_seconds
Merge pull request #1596 from Ichimonji10/bz-1154803

Skip known-failing test (see BZ 1154803)
Drop method update_dictionary

Method `update_dictionary` behaves almost exactly like the `update` method from
the standard library. Consider these two lines of code:

    d1.update(d2)
    update_dictionary(d1, d2)

In the first case, `d1` will receive all keys from `d2`:

    >>> d1 = {1: 10, 2: 20}
    >>> d2 = {2: 25, 3: 30}
    >>> d1.update(d2)
    >>> d1
    {1: 10, 2: 25, 3: 30}

In the second case, `d1` will receive only intersecting keys from `d2`:

    >>> d1 = {1: 10, 2: 20}
    >>> d2 = {2: 25, 3: 30}
    >>> update_dictionary(d1, d2)
    >>> helpers.update_dictionary(d1, d2)
    {1: 10, 2: 25}

`update_dictionary` is used in two modules:

* robottelo.cli.factory
* robottelo.ui.factory

In the UI factory, the usage of `update_dictionary` is a no-op, as `update` is
called immediately afterwards. In the CLI factory, the usage of
`update_dictionary` appears to be useless, though this is not a logical
certainty.